Theories abound as to what went wrong between Mark Sanchez and Eva Longoria, but perhaps the fact that the Jets aren't playing so well had something to do with it.

Sources close to the pair allege that Mark wasn't so easy to be around while the Jets have performed poorly on the field. They're a lowly 3-4 and lost to the Patriots on Monday night (Oct. 21).

"It's hard to maintain a relationship when one person is upset all the time," says a source.

Maybe they should hook back up in the off-season.

[via TMZ]